In the 1940s improved microphone design allowed a more intimate singing style and ten or twenty years later inexpensive and more durable 45 r.p.m. Classically, a rock band takes the form of a quartet whose members cover one or more roles, including vocalist, lead guitarist, rhythm guitarist, bass guitarist, drummer and often that of keyboard player or other instrumentalist. The terms "popular music" and "pop music" are often used interchangeably, although the former is a description of music which is popular (and can include any style). Rock music is traditionally built on a foundation of simple unsyncopated rhythms in a 4/4 meter, with a repetitive snare drum back beat on beats two and four. Melodies are often derived from older musical modes, including the Dorian and Mixolydian, as well as major and minor modes. The dominance of rock by white, male musicians has been seen as one of the key factors shaping the themes explored in rock music.
Early pop music drew on the sentimental ballad for its form, gained its use of vocal harmonies from gospel and soul music, instrumentation from jazz, country, and rock music, orchestration from classical music, tempo from dance music, backing from electronic music, rhythmic elements from hip-hop music, and has recently appropriated spoken passages from rap. According to Grove Music Online, the term "pop music" "originated in Britain in the mid-1950s as a description for rock and roll and the new youth music styles that it influenced …". The Oxford Dictionary of Music states that while pop's "earlier meaning meant concerts appealing to a wide audience … Further fusion subgenres have since emerged, including pop punk, rap rock, and rap metal, as well as conscious attempts to revisit rock's history, including the garage rock/post-punk and synthpop revivals at the beginning of the new millennium.
Pop is not a do-it-yourself music but is professionally produced and packaged". records for singles "revolutionized the manner in which pop has been disseminated" and helped to move pop music to 'a record/radio/film star system'. Another technological change was the widespread availability of television in the 1950s; with televised performances, "pop stars had to have a visual presence". In the 1960s, the introduction of inexpensive, portable transistor radios meant that teenagers could listen to music outside of the home. Multi-track recording (from the 1960s); and digital sampling (from the 1980s) have also been utilized as methods for the creation and elaboration of pop music. By the early 1980s, the promotion of pop music had been greatly affected by the rise of Music Television channels like MTV, which "favoured those artists such as Michael Jackson and Madonna who had a strong visual appeal". Rock music is a genre of popular music that originated as "rock and roll" in the United States in the 1950s, and developed into a range of different styles in the 1960s and later, particularly in the United Kingdom and the United States. It has its roots in 1940s' and 1950s' rock and roll, itself heavily influenced by blues, rhythm and blues and country music. Pop music has been dominated by the American and (from the mid-1960s) British music industries, whose influence has made pop music something of an international monoculture, but most regions and countries have their own form of pop music, sometimes producing local versions of wider trends, and lending them local characteristics. Some of these trends (for example Europop) have had a significant impact of the development of the genre. Rock music also drew strongly on a number of other genres such as electric blues and folk, and incorporated influences from jazz, classical and other musical sources. In the 1940s improved microphone design allowed a more intimate singing style and ten or twenty years later inexpensive and more durable 45 r.p.m. It is, "provided from on high (by record companies, radio programmers and concert promoters) rather than being made from below … Such elements include generally short to medium-length songs, written in a basic format (often the verse-chorus structure), as well as the common employment of repeated choruses, melodic tunes, and hooks. In the second half of the 1970s, punk rock reacted against the perceived overblown, inauthentic and overly mainstream aspects of these genres to produce a stripped-down, energetic form of music valuing raw expression and often lyrically characterised by social and political critiques.